consoles: polling support, kgdboc

polled console handling support, to access a console in an irq-less
way while in debug or irq context.

absolutely zero impact as long as CONFIG_CONSOLE_POLL is disabled.
(which is the default)

[ jan.kiszka@siemens.com: lots of cleanups ]
[ mingo@elte.hu: redesign, splitups, cleanups. ]

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 85c95cd39bc3..21f69aca4505 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -125,6 +125,7 @@
 #include <linux/cdev.h>
 
 struct tty_struct;
+struct tty_driver;
 
 struct tty_operations {
         int  (*open)(struct tty_struct * tty, struct file * filp);
@@ -157,6 +158,11 @@ struct tty_operations {
         int (*tiocmget)(struct tty_struct *tty, struct file *file);
         int (*tiocmset)(struct tty_struct *tty, struct file *file,
                         unsigned int set, unsigned int clear);
+#ifdef CONFIG_CONSOLE_POLL
+        int (*poll_init)(struct tty_driver *driver, int line, char *options);
+        int (*poll_get_char)(struct tty_driver *driver, int line);
+        void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
+#endif
 };
 
 struct tty_driver {
@@ -220,6 +226,11 @@ struct tty_driver {
         int (*tiocmget)(struct tty_struct *tty, struct file *file);
         int (*tiocmset)(struct tty_struct *tty, struct file *file,
                         unsigned int set, unsigned int clear);
+#ifdef CONFIG_CONSOLE_POLL
+        int (*poll_init)(struct tty_driver *driver, int line, char *options);
+        int (*poll_get_char)(struct tty_driver *driver, int line);
+        void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
+#endif
 
         struct list_head tty_drivers;
 };
@@ -230,6 +241,7 @@ struct tty_driver *alloc_tty_driver(int lines);
 void put_tty_driver(struct tty_driver *driver);
 void tty_set_operations(struct tty_driver *driver,
                         const struct tty_operations *op);
+extern struct tty_driver *tty_find_polling_driver(char *name, int *line);
 
 /* tty driver magic number */
 #define TTY_DRIVER_MAGIC                0x5402